Problem 39 - Chemistry Matter and Change

Question

Challenge When aqueous solutions of sodium carbonate and manganese(V) chloride are mixed, a precipitate forms. The precipitate is a compound containing manganese.

Step-by-Step Solution

Answer

The balanced chemical equation for the reaction between sodium carbonate (Na2CO3) and manganese(V) chloride (MnCl5) is: Na2CO3(aq) + MnCl5(aq) → 2 NaCl(aq) + MnCO3(s) The precipitate formed is manganese carbonate (MnCO3).

Step 1: Identify the formula of the reactants and products

In this reaction, we have sodium carbonate, Na2CO3(aq), and manganese(V) chloride, MnCl5(aq), as reactants. When these two react, a double displacement reaction will occur. The sodium will displace the manganese in the manganese(V) chloride and vice versa. We will get sodium chloride (NaCl) and a manganese compound as products.

Step 2: Write the balanced chemical equation

Now that we have the formulas for the reactants and products, let's write the balanced chemical equation: Na2CO3(aq) + MnCl5(aq) → 2 NaCl(aq) + MnCO3(s) Make sure the number of atoms of each element is the same on both sides of the equation.

Step 3: Identify the precipitate by identifying the least soluble product

We know that the precipitate is a compound containing manganese, which is manganese carbonate, MnCO3(s), in this reaction. Sodium chloride (NaCl) is soluble in water and remains in solution. Therefore, the precipitate formed is manganese carbonate (MnCO3).

Key Concepts

Double Displacement Reaction

In the world of chemistry, a double displacement reaction is a fascinating event. It's like a dance where the partners switch places. This type of reaction involves two compounds, usually in aqueous solution, swapping parts when they react. For example, in our reaction with sodium carbonate ( \( \text{Na}_2\text{CO}_3 \)) and manganese(V) chloride ( \( \text{MnCl}_5 \)), the sodium ions will exchange with the manganese ions.

• Resulting new compounds are sodium chloride ( \( \text{NaCl} \)) and manganese carbonate ( \( \text{MnCO}_3 \)).
• Each ion keeps its charge and combines with the anion or cation it meets.

The key idea here is that each substance starts as part of a compound and forms new bonds with the ions from the other compound. The ions swap, but the total charge is conserved, which is essential for balancing chemical equations.

Precipitation Reaction

Whenever you see solid forming from a solution, you might be witnessing a precipitation reaction. These reactions occur when two aqueous solutions combine and form a solid product. The solid, known as a "precipitate," emerges because it's not soluble in water.In our specific example, when the two solutions, sodium carbonate and manganese(V) chloride, react, manganese carbonate emerges as a solid precipitate.

• The manganese carbonate ( \( \text{MnCO}_3 \)) comes out of the solution as it is not soluble.
• This leaves sodium chloride still dissolved in the solution as it remains soluble.

Precipitation reactions are an easy way to separate a compound from a solution.

Manganese Carbonate

Manganese carbonate, represented by the formula ( \( \text{MnCO}_3 \)), is a well-known compound in chemistry. This compound forms as a white to pale pink solid that can be identified quite easily once precipitated in reactions, like the one we've explored.

• Manganese carbonate is typically not soluble in water, which leads it to form a precipitate in reactions.
• Its formation in a reaction helps scientists identify it based on its solubility properties.

Understanding manganese carbonate in reactions is crucial, especially in identifying the necessary conditions to form this compound.

Balancing Chemical Equations

Balancing chemical equations ensures the law of conservation of mass is followed, meaning the number of each type of atom on both sides of the equation must be equal. It's like ensuring everyone who attends a party leaves as well. When you write an equation, start by noting the number of each atom present in the reactants and products, then adjust the coefficients to balance the equation. For our example:

• Na: Needs to balance the 2 sodium atoms in Na2CO3 and NaCl.
• Cl: 5 chlorines in MnCl5 must match on the product side as 5 NaCl units, hence multiplying NaCl by 5.
• Mn and CO3: Balances between reactant manganese chloride and product manganese carbonate.

Be meticulous in balancing, as it's vital for accurately representing the reaction and ensuring mass is conserved.